That's the million dollar question isn't it? I think that the most talked about are the most expensive (ghi, trick, etc) but that doesn't necessarily make then 'hot' because most people can't afford them.
I think that the bits and pieces to make sweet combos are probably what people are looking for right now. Enchi, pied, clown, phantom, mystic, and so on.
My list is HUGE but the list of things that I can realistically afford isn't hahaha